Graphene represents a form of carbon in which the carbon atoms reside within a single atomically thin sheet or a few layered sheets (e.g., about 20 or less) of fused six-membered rings forming an extended planar lattice. In its various forms, graphene has garnered widespread interest for use in a number of applications, primarily due to its favorable combination of high electrical and thermal conductivity values, good in-plane mechanical strength, and unique optical and electronic properties. Of particular interest to industry are large-area graphene films for applications such as, for example, special barrier layers, coatings, large area conductive elements (e.g., RF radiators or antennas), integrated circuits, transparent electrodes, solar cells, gas barriers, flexible electronics and the like.
Some envisioned applications for graphene and other two-dimensional materials are predicated upon introducing defects, such as forming a plurality of nanometer-scale holes in the planar structure. For example, the hole density of perforated graphene can be used to tune the electrical conductivity of this nanomaterial and in some instances can be used to adjust its electronic band structure. Filtration applications are another area where perforated graphene and other perforated two-dimensional materials have generated considerable interest. Due to the atomic-level thinness of graphene and other two-dimensional materials, it is possible to achieve high fluid throughput fluxes during filtration processes.
A number of processes are known for perforating and/or defecting graphene and other two-dimensional materials (e.g., ion bombardment, oxidation, nanoparticle bombardment, etc.). Likewise, a number of techniques for healing holes, that are too large for a given application, in graphene and other two-dimensional materials have been disclosed (see, for example, US patent application filed herewith, entitled METHOD FOR MAKING TWO-DIMENSIONAL MATERIALS AND COMPOSITE MEMBRANES THEREOF HAVING SIZE-SELECTIVE PERFORATIONS, U.S. Pat No. 15/099,482 incorporated herein in its entirety). However, production of holes with a desired size range, a narrow size distribution, and a high and uniform hole density remains a challenge, at least partially, due to small physical and chemical inconsistencies from sheet-to-sheet of the two-dimensional material (e.g. layers, intrinsic or native defects, strain, electron distribution and crystallinity) and surface contamination. Currently, there is no way to monitor and adjust perforation or healing conditions in real-time. Instead, samples are perforated or healed, then tested by a separate process, and perforation or healing parameters are adjusted and applied to a new sheet of material, which inevitably possesses chemical and physical variations that cause it to respond differently to the new conditions. For example, contamination from sample to sample may vary, and needs to be accounted for. Typically to validate a perforation process, graphene needs to be transferred simultaneously to multiple TEM grids and to a desired support substrate. The TEM grids are then exposed to various different treatments. These must then be individually loaded into an STEM and imaged to determine the perforation results. If one of the conditions turns out to be appropriate, the the graphene on the support substrate is then subjected to the same treatment.
In view of the foregoing, methods that monitor and adjust for inter- and intra-sheet variability during perforation or healing of graphene and other two-dimensional materials would be of considerable interest in the art. In particular, methods for real-time, in situ monitoring of defect formation or healing would be of considerable interest in the art. For example, monitoring of defect formation or healing for suspended graphene would be of interest. The present disclosure satisfies the foregoing needs and provides related advantages as well.